The storage of potatoes, and other tubers, is typically done at a temperature between 2 and 10° C. At this temperature the potato converts starch into sugar and stores the sugar in the potato leading to a sweeter taste and in the French fries test, the potato collars brown to fast when cooked (fry colour). This leads to a lower quality of potato. The cure to the build-up of sugar in the potato is to store the potatoes at a higher temperature, preferably around 15° C. a couple of weeks before the potatoes are put on the market. In this period the sugar level with in the potato will drop, but the potato will start to produce sprouts or germs. Along with the sprout formation, the potato will start to produce toxic glycoalkoids, molecules that are not destroyed during cooking, making the potato unsellable. Some potato storages are not equipped with a climate control until and the temperature within the storage depends on the weather condition. If the temperature within the ware house can't be kept low enough, the potatoes will start to sprout. To suppress sprouting, sprouting inhibitors are used.
The sprout inhibitor of choice over the last 50 years is 3-chlorophenylisopropylcarbamate (CIPC) also known as chlorpropham, CAS 101-21-3. CIPC brings the potato or tuber in a dormant state with very little sprout formation. CIPC is a solid at room temperature; this property causes CIPC to attach to potatoes and leaving residues on the treated potatoes for a long time after application. CIPC use in Europe is restricted to max. 36 g active ingredient per ton potatoes per year.
CIPC residue-levels are subjected to regulations. As part of the European Annex I inclusion under Directive EC/91/414 a Maximum Residue Level (MRL) of 10 mg/kg was set. Expectations are that the MRL level will continue to be lowered, demanding for alternative treatment of tubers, preferably potatoes. In addition, there is a growing bio-segment, which demands fresh produce absent of residues. Consequently, alternatives are sought to be able to lower CIPC use, meet residue level requirements, and keep efficacy.
U.S. Pat. No. 5,811,372 described a method for the anti-sprouting treatment of potatoes by the application of CIPC and a terpene by hot fogging. An efficacy test is included wherein a range of terpenes is tested in combination with CIPC. A good result was obtained for carvone. The combination of CIPC and limonene was reported as not effective and even worse than the application of CIPC alone. At 125 days after treatment, a combined use of 16.6 ppm CIPC with 16.6 ppm limonene showed 97% unsuitable for fresh pack use. Tubers having sprouts which on average are greater than 1 mm were considered unacceptable for fresh pack.
Apparently, limonene is not a candidate for CIPC replacement.
More recently, US 2006/0276336 (EP 1 728 429) described a method for the anti-sprouting treatment of tubers by application of CIPC and a terpene or an essential oil via hot fogging. The terpene of choice was carvone, eugenol or iso eugenol obtained from clove oil or mint oil. However, clove oil and its derivatives are likely to be cost-prohibitive, demanding a cheaper more economical alternative. In this document it is repeated that limonene in a combination with CIPC is not effective in inhibiting sprout formation. In the treatment of tubers, 20 grams per tonne of CIPC is used in combination with carvone or (iso)eugenol. Combinations of CIPC with limonene or jasmonene were disclosed as not providing positive results.
In WO 00/32063 a fog treatment method is disclosed using a liquid composition for the treatment of potatoes. One of the examples uses a 60 wt % limonene composition with 7 wt % non-ionic emulsifier and 33 wt % butyl acetate solvent. The treatment protocol consisted of 45 g/ton at the start of storage and 15 g/ton every 20 days, thereby delivering 165 g of active ingredient per ton of potatoes over a 6 month period. After a period of 5 months the limonene treated potatoes showed weight loss (4.5% vs 5.4%) and sprout growth (96.8% vs 100%; compared to 18% for CIPC) close to that observed for the untreated control. This disclosure presents limonene as unsuitable for sprout control in potatoes.
It is an objective of the present invention, to provide a solution to at least one of the problems mentioned above.
The invention aims to provide a composition for use as an anti-sprouting agent, capable of at least partially replacing CIPC as anti-sprouting agent for potatoes. The alternative should be cost effective. Preferably the alternative is renewable. It would be advantageous if the alternative could reduce the amount of residues of CIPC.